The detailed mechanisms underlying the fundamental membrane events involved in the visual process will be investigated at the sub-molecular level by x-ray and neutron diffraction and nuclear magnetic resonance and optical spectroscopy. These studies center initially on a determination of the dynamical structure at the sub-molecular level of the rhodopsin-containing retinal receptor outer segment disk membrane and the nerve axonal disk membrane. The dynamical structure of the natural and structurally modified membranes together with their various structurally modified functionally relevant model membranes will be studied "at rest" and during the time course of their natural or artificially perturbed visual function. "Functionally relevant" here refers to model membranes which exhibit selective light-modulated, chemical-modulated and electric field-modulated ion permeabilities. The detailed mechanisms will primarily be determined through a correlation of systematic time-independent and time-dependent dynamical-structural variations of the membranes with their resulting modified functionality. BIBLIOGRAPHIC REFERENCES: Blasie, J.K., Zaccai, G., and Schoenborn, B.P., Brookhaven Symposium in Biology "Neutron Scattering for the Analysis of Biological Structures", no. 27, 1975. Podo, F., and Blasie, J.K., Biochim. Biophys. Acta Biomembranes, 419, 1, 1976.